Cultivators am used to cultivate ground but with a move to trash farming or farming in which stubble and straw is left on the ground then cultivators which are normally dragged across the ground get easily clogged with such straw and stubble and become ineffective. Prickle chain harrows which consist essentially of a chain with a number of spikes extending from it which are dragged across the ground at an angle to transverse to the direction of travel of the cultivator to give a rolling motion provide a degree of cultivation but the tines can easily get blocked up with trash. Further, the weight of such a chain can be insufficient to cause sufficient ground working for suitable cultivation in some types of soils.
Australian Patent specification No. 612,585 published 21 st Jan. 1988 discloses a ground working tool which has groups of tool elements connected longitudinally together to form a chain which when held in tension form a prickle chain. Each tool element has at least one tine extending radially out from it. Although there are significant advantages in having a chain system in which an assembly is made up of a series of replaceable links there are several problems with the system disclosed. A first problem is that the number of tool elements in each group is restricted to two or three because they need to touch each other to provide mutual support and any greater number would form an unstable group which would collapse under conditions of use. Other problems which exist are that the total weight of the chain is insufficient to provide ground working in other than quite light soils and the maximum possible diameter does not allow for good ground entry, track of cultivation and trash clearance. Extending the lengths of the tines to give a greater diameter is impractical because longer tines are liable to break.
It is the object of this invention to provide an implement suitable as a rolling or rotating type cultivator which can have a greater overall diameter than existing prickle chain harrows and hence will not catch so much trash and which can have sufficient weight to provide good cultivation.